I just bought 'The Haskell School of Expression', so I downloaded the latest version of Hugs98, February 2001, and the latest version of the Hugs Graphics Library, 2.0.3. Since the documentation mentioned building on Linux, I built and installed hugs98, ran some tests and felt it was okay. This is on a Redhat Linux 6.0 installation. Then I built the Hugs Graphics Library, and tried to run the first test suggested: ======================================================================= <1122:~/tmp/haskell> runhugs -Pgraphics-2.0.3/lib/x11: graphics-2.0.3/demos/HelloWorld.hs runhugs: Error occurred Reading file "graphics-2.0.3/demos/HelloWorld.hs": Reading file "graphics-2.0.3/lib/x11/GraphicsUtils.hs": Reading file "graphics-2.0.3/lib/x11/GraphicsCore.hs": Reading file "graphics-2.0.3/lib/x11/GraphicsEvent.hs": Reading file "graphics-2.0.3/lib/x11/GraphicsWindow.hs": Reading file "graphics-2.0.3/lib/x11/Xlib.hs": Reading file "graphics-2.0.3/lib/x11/StdDIS.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Int.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Bits.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Int.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Word.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Addr.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/Monad.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Foreign.hs": Reading file "graphics-2.0.3/lib/x11/StdDIS.hs": Reading file "graphics-2.0.3/lib/x11/X.hs": Reading file "graphics-2.0.3/lib/x11/Xlib.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Concurrent.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/ChannelVar.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/ConcBase.hs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/ChannelVar.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Channel.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Semaphore.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/SampleVar.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/exts/Concurrent.lhs": Reading file "/user/donw/tmp/haskell/Hugs.ixl/share/hugs/lib/System.hs": Reading file "graphics-2.0.3/lib/x11/Graphics_Utilities.hs": Dependency analysis ERROR graphics-2.0.3/lib/x11/Graphics_Utilities.hs:73 - Illegal type "IOResult a" in constructor application <1123:~/tmp/haskell> pushd graphics-2.0.3 ~/tmp/haskell/graphics-2.0.3 ~/tmp/haskell <1125:~/tmp/haskell/graphics-2.0.3> find . -name '*hs' -print | xargs grep IOResult ./lib/x11/Graphics_Utilities.hs: mkErr :: Maybe (IOResult a) -> IOError ./lib/win32/GraphicsUtilities.hs: mkErr :: Maybe (IOResult a) -> IOError ======================================================================= I couldn't find a discussion of IOResult in the html versions of the Haskell 98 report or library report, but it is in the prelude: ======================================================================= ./lib/Prelude.hs:data IOResult ======================================================================= I'm still learning all the ins and outs of Haskell, so I don't really know what the problem is. Any helpful hints? -- Don Wakefield Mentor Graphics Corporation (503) 685-1262 8005 S.W. Boeckman Road don_wakefield@mentorg.com Wilsonville, OR 97070-7777